Keystone chain



Oct. 13, 1942. J B WEBB 2,298,604

KEYSTONE CHAIN Filed Sept. 12, 1939 OLD 472T 5 INVENTOR.

ATTORN JER V/S N TED-i. S

Patented 3: I

Es PATENT". OFFICE Q KEYSTONE cnsm' Jervis B. Webb, Bloomfield Hills, Mich. Application September 1:. 1939, Serial No. 294,51e

4 Claims. (01. 14-254) The invention described herein relates to an improved form of chain of'the type disclosed in U. S. Letters Patent No. 870,704 and such as has been widely used for many years for various industrial purposes and particularly for conveying equipment.

This chain, commonly known as keystone chain,.

consisting of a series of links connected at each end by pins to two side bars, performs a dual function, the trolley units being attached to some of the links, depending upon the spacing desired, while the side bars are designed so that the teeth of the large sprocket wheels which drive and guide these conveyors can fit between each pair of them and bear against the ends of the links.

The objections to the type of keystone chain now in use can best be understod from a study of Fig. 5 of the drawing accompanying this specification which shows a section of chain composed of a link ll connected by the pin II to two side bars i3. These side bars are formed with enlarged end portions having notches ii in which the heads of the pin l2 are supposed to seat.

where than at the end portions H is such that it is possible for the pin l2 to take the incorrect position shown, either because of careless work in first assembling the link and side bars or careless handling of the chain before it has been secured to the conveyor and brought to its proper length. If for any reason a pin should be placed as shown, the results are obvious; the teeth of the sprocket wheels cannot properly contact the adjacent -links,-a large amount of backlash is possible inthe chain which will interfere with the driving of the conveyor and cause abnormal strain on the pins, and lastly, during this backlash the pin is likely to revolve about 90 degrees and drop out, thus putting the entire conveyor line out of commission until repairs can be made.

With this situation in mind, the principal object of this invention is to provide a type of conveyor chain, the elements of which can only be associated in one proper assembled relationship.

A second object is to provide a design of side bar for conveyor chain which will protect the pins holding such sidebar to the connecting links from wear when the chain is used in installations where it comes in contact with a supporting surface. a

A further object is to accomplish the desiredresult by means which will have no appreciable efiect upon the manufacturing cost of this conveyor chain.

Fig. 1 is a plan view showing the elements comprising a section of conveyor chain consisting of, from leftto right, a link, a pin, and the side bars.

Fig. 2 is a side elevation of the structures shown in F G. 1. v

1 1g. 3 shows,-in side elevation, the structures of Figs. 1 and 2 being assembled.

Fig. 4 shows the assembly of Fig. 3 completed.

Fig. 5, as previously mentioned, shows a side elevation of the elements comprising the old type of conveyor chain in an improper assembled condition.

In the improved form of chain shown in Figs. 1 to 4 inclusive, the link I6 and pin l'l are of substantially the same design as the link II and pin i 2 of the old type chain shown in Fig. 5, the link I being oblong in shape with its sides I8 forming bosses I! at each of its ends and symmetrical about its longitudinal axis. I-shaped, having a circular shank 20, of a diameter smallerthan the inside width of the link, connecting the rectangular heads 2| whose width is such that they will fit within the notches 22 extending transversely at each end of the side bars 23. As can'be seen from the plan view of Fig. 1, these side bars have an oblong shape similar to that of the link I6, divided by the transverse stiflening member 24. The side portions 25 of these side bars are built up to uniform depth equal to that surrounding the notches 22, except for the small sections adjacent. the stiffening member 24 which are relieved to facilitate the forging work.

By reason of the depth of these side bars, it

1 becomes impossible, when assembling this chain,

to place the pin II in any other position but a correct one where its heads are engaged by the notches 22 because the length of the shank 20 of the pin is not great enough tobridge the combined depth of the boss is of the link l6 plus the depth of the side bars except at the places where the notches 22 are provided.

4 Chain of the keystone type is frequently used 'in driving other material-handling equipment than overhead conveyors, and in connection with theseother uses the chain is often positioned so that it drags upon a supporting surface in performing its driving function. When the chain is low to the ground or other supporting surface and In the drawing accompanying this specification, thus out of the way. In actual practice with this drags.

- of said pins, the length of the shank portion of localized at the end portions ll of the side bars I and upon the heads of the pins l2 and because of the small area of these surfaces subjected to this abrasive action the heads of the pins l2 would be worn away within a relatively short Period of time.

The improved side bars 23 of the chain of the present invention have been designed to relieve the extent of the wear produced by the abrasive action between the chain and a supporting surface and'especially to protect the heads of the pins.

It will be seen from the drawing, particularly Fig. 4, that the head 2| of the pin'l 1, which rests within the notch 22 extending transversely of the side bar, is protected from wear by the side portions 25 of the side bar, which provide a large area over which this wear may be distributed. These side portions 25 can be said to perform the function of a walepiece. It is obvious that in the design of side bars constructed according to the principles of this invention, the depth of the walepieces can be varied at will according to the amount of abrasive wear to which the chain'will be subjected in any particular installation. Consequently, th life of the chain can be increased greatly over that expected from now commonly employed.

1 claim: v

l. A conveyor chain composed of a series of links each of which is'connected to its adjacent link by a pair of side bars, said links and side-bars having longitudinal slotted portions terminating near the ends thereof,-headed pins iii-said slotted portions holding said links and sidebars together, said links having raised bossportions at each of their ends, saidside, bars being positioned adjacent said boss portions when said links and side bars are in operative relation, said side bars having built-up side portions adjacent the slotted portions thereof, said built-up. side portions being cut away near the ends of said side bars toform recesses adapted to receive the heads of said pins whereby the combined depth of the said boss portion of said link and said Pair of side bars is greater than the distance intermediate the heads of said pins at all possible positions where said pins could traverse except at I said recesses of said side bars.

2. A conveyor chain composed of a series of links, each of which is connected to its adjacent link by a pair of sidebars, said links each having a longitudinal slotted portion, said side bars each having slotted portions extending longitudinally and terminating near the ends thereof, pins in said slotted portions holding said links and side bars together, said pins having a shank portion with heads at the ends thereof, said links having raised boss portions at each of their ends and a narrower side portion extending therebetween, said side bars being positioned adjacent said boss portions when said links and side bars are in operative relation, said side bars having built up side portions adjacent the slotted portions thereof, said built up side portions being cut away near the ends of said side bars to form forms of chain transverse recesses adapted to receive said heads is said pins being'substantially equal to the combined dimension across the said boss portion of saidlinkfromthesuriaceofthesaidrecessed portion of one of said pair of side bars to the sur-.

of their ends, said side bars being positioned adjacent said boss portions when said links and side bars are in operative relation, said side bars having a walepiece extending alongthe length thereof, said walepiece being cut away near the ends of said side bars to form recessed portions adapted to receive said heads of said pins, the outer surface of said heads of said pins lying below the outer surface of said walepiece whereby the combined depth of the said boss portion ofsaidlinks'and said pairofside barsisgreater than the length of the said shank portion of said pins at all possible positions where said pins could traverse except at said recesses of said side bars.

4. A conveyor chain consisting of a series of links each of which is connected to its adjacent links by a pair of side bars, said links and side bars having longitudinally extending elongated openings terminating near the-ends thereof, said links having a raised boss portion at each of their, ends, detachable pins for connecting said side bars and linksin assembled condition to form a continuous chain, said pins each being provided with a shank portion and a pair of integral elongated heads adapted when placed longitudinally to pass freely through said elongated openings of said links and side bars, each of said side bars being provided near the ends thereof with transversely extending recesses adapted to receive the'heads of. said pins when the latter are turned at right angles to the longitudinal center lineofsaidlinks, andsaidlinkshavingthecentral portion thereof between said end bosses reduced to a thickness such that when said pins are inserted through said openings of said side bars and links said pins may b turned to engage within said recesses. the length of the shank portion of each of said pins being substantially equal to the combined dimension across a boss portion of one of said links from the surface of the recessed portion of one of said side bars to the surface of therecessed portion of the other of said pair of side bars and said side bars adjacent said elongated openings intermediate said recesses having athickness such that the combined dimension thereof and the thickness of a link across said boss portion is substantially greater than the length of the shank portion of one of said pins whereby the heads of said pins can be positioned transversely to said side bars for holding said side bars with the ends thereof in proper assembled relationship to the boss portions of said links only when the headed portions of said pins are seated within the recessed portions of said side bars at the ends thereof.

saavrs B. wane. 

